Proposed changes by Chicago police to its policy on use of force fail to spell out that deadly force should be a last resort and fall short of other key goals such as limiting Taser use and improving transparency, two leading police reform experts say.

In comments submitted to the department Monday, Sheila Bedi, a professor with Northwestern University's MacArthur Justice Center, and Craig Futterman, a law professor at the University of Chicago, said the overhaul doesn't go far enough in spelling out clearly when officers can use force, particularly deadly force.

The policy should begin with the premise that physical encounters with civilians are appropriate only when there is probable cause for arrest or a public safety emergency, Futterman and Bedi said. The policy also needs to be clear that the department's highest priority is the sanctity of life and that deadly force is "a matter of last resort" used only to protect the lives of officers and citizens, they wrote.

"The policy should delete terms such as 'reasonably believes' or 'reasonably necessary' because they are confusing and fail to provide clear guidance to officers," they wrote.

A Chicago police spokesman said Tuesday the department had not had a chance to review the recommendations that Bedi and Futterman submitted just under a Monday night deadline. At least 300 total comments were submitted over the past six weeks, the spokesman said. The feedback will be reviewed before any changes are completed, Superintendent Eddie Johnson has said.

The department's draft policies were unveiled in October amid pressure from a U.S. Justice Department investigation and public outrage over police misconduct that boiled over with the release last year of the Laquan McDonald shooting video. Among other changes, the proposals sought to limit when officers can shoot fleeing people, restrict the number of times officers can Taser arrestees and compel officers to use the lightest force possible in any situation.

In a brief interview Tuesday, Futterman commended the department for putting emphasis on de-escalating conflicts, but he said it's crucial that any new policies make it absolutely clear when the use of force is justified.

"Confusing policies aren't fair to the police or to the public," Futterman said. "So I sympathize with (officers)."

Bedi, meanwhile, said it was unclear how much attention, if any, the department would pay to the comments.

"We hope we will have a transparent process, and the department will take the analysis of many members of the community seriously," she said.

In addition to the use-of-force directives, Futterman and Bedi also criticized the lack of safeguards to ensure transparency and oversight after shootings.

The new policies should make it a "default practice" to release video and other relevant information to the public within 48 hours of a shooting incident. If an ongoing investigation could be compromised, the release of information should come within 14 days, they said.

They called on giving control of police shooting scenes to the new Civilian Office of Police Accountability — which the mayor proposed as a replacement for the much-maligned Independent Police Review Authority — instead of the Police Department.

The proposed rules governing the use of Tasers and chemical sprays also need to be reconsidered, Futterman and Bedi said. As written, the proposed policy allows officers to use Tasers on unarmed people walking away from police as well as citizens who are a potential harm only to themselves. Sprays could be used on anyone who disobeys an officer's command even if they don't pose a threat, they said.

Futterman and Bedi recommended that the policy forbid the use of Tasers or sprays on people older than 60 or younger than 18, as well as pregnant women.

The changes to the use-of-force policies are the latest aftershock of the court-ordered release in November 2015 of dashboard camera video of white Officer Jason Van Dyke shooting McDonald, an African-American teen, 16 times as he appeared to walk away from officers while carrying a knife. The video touched off sustained protests fueled by decades of frustration among many black Chicagoans over use of force and the failure to discipline officers.

Police officials have said they hope to adopt the new rules by the end of the year and then train the city's estimated 12,000 sworn officers by spring, a potential change for a department that has sometimes shifted policy with little fanfare and has previously provided scant training to officers after the academy.

The Justice Department, meanwhile, is investigating whether Chicago police have systematically abused citizens, and Mayor Rahm Emanuel has worked to enact changes to policing and discipline aimed at getting ahead of reforms that federal authorities might seek.

The ability of any new policy to bring change will depend partly on enforcement. Recent Tribune investigations have shown IPRA had has been sluggish and reluctant to find officers at fault, even when compelling evidence suggested wrongdoing.

COPA, which was approved by aldermen in October and will begin operations next year, is promised to have more funding and beefed-up authority.